Physical vapor deposition targets and methods of formation

ABSTRACT

A method includes combining a solid first material and a solid second material and melting at least a portion of the first material sufficient to coat the second material and any remaining first material. An approximately homogenous distribution of the second material can be formed throughout the liquid phase of the first material. The first material liquid phase can then be solidified to define a composite target blank exhibiting an approximately homogenous distribution of the solid second material in a matrix of the solidified first material. The first material can comprise SE and the second material can comprise Ge and/or Ag. The composite target blank can include at least about 50 vol % matrix. The first and second materials can be powdered metals. Accordingly, a physical vapor deposition target can include a matrix of a first material and an approximately homogenous distribution of particles of a second material throughout the first material matrix. The second material can include powders exhibiting particles sizes no greater than about 325 mesh.

TECHNICAL FIELD

[0001] This invention relates to methods of forming physical vapordeposition targets and sputter deposition targets, to targets producedby such methods, to films produced by such targets, and, additionally,to targets independent of their method of formation.

BACKGROUND OF THE INVENTION

[0002] Germanium selenide is a member of the chalcogenide class ofcompounds. Films of these compounds have been used in the manufacture ofcomputer memory devices. Memory densities in excess of 340 Mbits/cm²have been demonstrated with germanium selenide films with a minimumsingle layer feature size of approximately 0.18 micrometers.

[0003] Chalcogenides are finding utility in the manufacture ofprogrammable metallization cells which have the potential for playing asignificant role in future generations of computer memories. Thus,efficient formation of germanium selenide films with known andreproducable stoichiometries is an important goal. Germanium selenidefilms are typically formed by co-sputtering pure germanium and pureselenium targets. Simultaneous sputtering of both targets is carried outwith simultaneous deposit of Ge and Se onto a common substrate, therebycreating a film containing both germanium and selenium

[0004] However, the co-sputtering formation of germanium selenide filmsrequires complex sputtering equipment, increasing processing costs.Also, precise control of two separate sputtering processes to achieveadequate film homogeneity, film uniformity, and film stoichiometry.Achieving such objectives in a production environment, as opposed to alaboratory environment, presents a significant and costly challenge.

SUMMARY OF THE INVENTION

[0005] According to one aspect of the invention, a method includescombining a solid first material and a solid second material and meltingat least a portion of the first material sufficient to coat the secondmaterial and any remaining first material. The melted portion can definea first material liquid phase. An approximately homogenous distributionof the second material can be formed throughout the first materialliquid phase. The first material liquid phase can be solidified todefine a composite target blank that includes an approximatelyhomogenous distribution of the second solid material in a matrix of thesolidified first material. As an example, the first and second materialscan include metals. The first material can comprise Se and the secondmaterial can comprise at least one of Ag or Ge. The melting of at leasta portion of the first material and the forming cf an approximatelyhomogenous distribution can occur together and be accomplished by hotpressing. The composite target blank can include at least about 50volume % (vol %) matrix. The melting can occur in a vessel while heatingand compressing the first material. In such case, the first materialliquid phase can exhibit a sufficiently high viscosity to prevent asubstantial amount of the first material liquid phase from escaping thevessel during compression. Similarly, the viscosity of the firstmaterial liquid phase can prevent a substantial amount of secondmaterial from settling out of the approximately homogenous distributionin the first material liquid phase. By such methods, a composite targetblank can be obtained that exhibits a bulk density of at least about 95%of theoretical density.

[0006] According to a further aspect of the invention, a physical vapordeposition target forming method can include combining a first powdercomprising a first metal with a second powder comprising a second metal.The first metal can exhibit a melting point at least about 100 Celsius(° C.) less than a melting point exhibited by the second metal. Heat andpressure can be applied to a first volume including the combined firstand second powders, changing the first volume to a second volume. Thesecond volume can include at least about 50 vol % liquid phase of thefirst metal. The second volume may be cooled into a composite targetblank having an approximately homogenous distribution of at least thesecond powder. The first and second powders can exhibit particle sizesno greater than about 325 mesh. Also, the method can further includescreening the first and second powders with a 100 mesh screen toseparate agglomerations. The applying heat and pressure can includeheating to a temperature of less than about the melting point of thesecond metal at a rate of from about 200 to about 400° C. per hour whileunder compression of from about 6.9×10⁶ to about 28×10⁶ Pascals (about1,000 to about 4,000 pounds/inch²). Also, the cooling of the secondvolume can include removing heat to obtain about an intermediatetemperature, maintaining about the intermediate temperature for fromabout 45 to about 90 minutes, and cooling further to a room temperatureof from about 20 to about 25° C. The intermediate temperature can beabout 200° C. Also, the applying heat can attain a temperature of about225° C. The first powder can include at least about 99.99 weight percent(wt %) Se on a metals basis and the second powder can include at leastabout 99.99 wt % Ag or Ge on a metals basis. The composite target blankcan further exhibit a bulk density of at least about 98% of theoreticaldensity.

[0007] In another aspect of the invention, a composite material caninclude a matrix of a first material and an approximately homogenousdistribution of particles of a second material throughout the firstmaterial matrix. Also, a physical vapor deposition target can include atleast about 50 vol % matrix and an approximately homogenous distributionof a powder throughout the matrix. The matrix can include a first metaland the powder can include a second metal. Still further, a sputterdeposition target can include a continuous matrix of Se encapsulating anapproximately homogenous distribution of a powder throughout the Sematrix. The powder can comprise at least about 99.99 wt % Ag or Ge on ametals basis. The target can comprise from about 25 to about 50 wt % ofthe at least one of Ag or Ge in the Se matrix.

BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Preferred embodiments of the invention are described below withreference to the following accompanying drawings.

[0009]FIG. 1 is a sectional view of a manufacturing device containingmaterials for formation of a deposition target.

[0010]FIG. 2 is a sectional view of the device in FIG. 1 at a processingstep subsequent to that depicted by FIG. 1.

[0011]FIG. 3 is a sectional view of the material of FIG. 2 at aprocessing step subsequent to that depicted by FIG. 2.

[0012]FIG. 4 shows a sectional view of a target/backing plateconstruction with target formed in accordance with methodology of thepresent invention. The construction corresponds to a large ENDURA™configuration.

[0013]FIG. 5 is a top view of the target/backing plate construction ofFIG. 4.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] The various aspects of the present invention are potentiallyapplicable to a variety of types of deposition targets and materials forsuch targets. For example, the aspects of the invention are applicableto physical vapor deposition (PVD) targets, including but not limitedto, sputter deposition targets. The specific examples provided hereindemonstrating application of the aspects of the invention describedeposition targets including Ge (and/or Ag) and Se, however, it isconceivable that the methods of the present invention may be used toform deposition targets of other metals, as well as non-metals, to theextent that such other materials are suitable for use in depositiontargets. Further, the inventions are not limited to PVD targets and themethods herein may be used to form composite materials suitable forother uses. In particular, composite Ge (and/or Ag) and Se materials maybe formed.

[0015] In one aspect of the invention, a method includes combining asolid first material and a solid second material. The first and secondmaterials can comprise metals. For example, the first material cancomprise Se and the second material can comprise at least one of Ag orGe. The method can further comprise combining at least one additionalsolid material with the solid first and second materials. Such combiningmay be accomplished wherein at least one of the first material and thesecond material comprise a plurality of chemical elements, for example,metallic elements. Alternatively, the first and second material can be,respectively, solid particles of the first and second materials andsolid particles of a third material can be added thereto. Nevertheless,most preferably the first material comprises at least about 99.99 weightpercent (wt %) Se on a metals basis. Similarly, the second material cancomprise at least about 99.99 wt % Ag or Ge on a metals basis.

[0016] In addition to the composition of first and second materials, thephysical appearance of such materials may be another consideration. Forexample, one of the typical goals in forming various types of depositiontargets is to produce a uniform or homogenous target material. In thecase of a single component target, for example a target comprising ahigh purity single metal, homogeneity is less of a concern. In amultiple component deposition target, such as a GeSe₂ or Ge₃Se₇ target,homogeneity can be difficult to obtain. A mixture of solid phases ofvarying compositions within a target having an overall or nominalcomposition typically detracts from the quality of a sputtered film. Forexample, in a conventional GeSe₂ target, some portions of the targetwill have a composition of GeSe₂ while other portions may have acomposition of GeSe, Ge₃Se₇, etc. Using such a mixed phase target in adeposition process often may not produce a film having the desired GeSe₂composition even though the nominal composition of the target is GeSe₂.

[0017] Forming a single phase GeSe₂ target can be accomplished byforming a liquid phase of GeSe₂ by methods known to those skilled in theart and quenching the liquid phase. Unfortunately, quenching typicallyproduces a shattered single phase GeSe₂ target. Such a target is notsuitable for a deposition process. Accordingly, the single phase targetis ground into fragments and hot pressed into a target shape. The hotpressing accomplishes solid phase bonding among the fragments of singlephase GeSe₂. Little or no melting during the hot pressing occurs sinceGeSe₂ exhibits a melting point of about 710 Celsius (° C.). In addition,the processes known to those skilled in the art for forming a liquidphase exhibiting a single phase of GeSe₂ are complex and costprohibitive for most applications in which deposition of GeSe₂ isdesired.

[0018] During development of the present invention, it was discoveredthat the first and second material discussed above are preferably in theform of solid particles. Such particles can be in a variety of shapesand sizes and still achieve at least part of the various aspects of theinvention described herein. For example, the first and second materialscan exhibit particles sizes no greater than about 100 mesh as measuredby methods known to those skilled in the art. More preferably, the firstand second materials are in powder form having similar sized particlesamong the first material and the second material. The powders can beconducive to mixing into a combined first and second material having anapproximately homogenous distribution of both materials throughout thevolume containing the first and second materials. Most preferably, suchpowders exhibit particle sizes no greater than about 325 mesh asmeasured by methods known to those skilled in the art. Experience hasindicated that the particle size range of no greater than about 325 meshprovides a sufficiently distributed concentration of Ge (and/or Ag) andSe to form films having a composition adequately near the nominalcomposition of the target. However, it is conceivable that other sizeranges higher or lower may be desired depending on sputter conditionsand target blank composition for Ge/Se and Ag/Se composite targets aswell as other composite targets. A sufficient distribution of particlespreferable keeps compositional variations throughout a target withinabout +/−5% of the nominal composition for a sample size of at leastabout 0.25 cm³. For example, in a GeSe₂ target blank, the atomic ratioof Ge to Se is preferably between from about 1:1.9 to about 1:2.1 at anypoint in the target.

[0019] During development of the invention, it was also discovered thatparticles can have a tendency to agglomerate, especially when exposed tomoisture. Agglomeration of particles prior to mixing first and secondmaterials can produce portions of a mixture having a disproportionateconcentration of at least one of the first and second materials. Forexample, Ge was shown to exhibit a higher tendency toward agglomerationin comparison to Se. One example of a suitable technique for controllingagglomeration is minimizing moisture exposure. Also, a deposition targetforming method can further include screening at least one of the firstand second materials to separate agglomerations. As an example, a 100mesh screen can be used. In this manner, any agglomerations of particlesin the combined first and second materials will exhibit a size nogreater than about 100 mesh. The screening process may also function tobreak up agglomerations into much smaller agglomerations or individualparticles.

[0020] The present aspect of the invention can next include melting atleast a portion of the first material sufficient to coat the secondmaterial and any remaining first material. The melted portion can definea first material liquid phase. The method can further include forming anapproximately homogenous distribution of the second material throughoutthe first material liquid phase. Preferably, the melting at least aportion of the first material and the forming an approximatelyhomogenous distribution can occur together and comprise hot pressing. Ina typical hot press process, solid phase bonding aided by the formationof a partial melt is desired and temperatures high enough to producesubstantial amounts of liquid phase are usually avoided. Because hotpressing involves compression in a die, production of a liquid phaserisks expelling at least some of the liquid from the die duringcompression.

[0021] In the case where Se and Ge are used as first and secondmaterials, liquid phase Se at a temperature near its melting pointtypically exhibits a sufficiently high viscosity that compression duringhot pressing does not expel liquid phase Se from a die. Accordingly, theinventors have discovered that temperature controls during hot pressingpotentially allow for melting of at least a portion of the firstmaterial sufficient to coat the second material without expelling thefirst material liquid phase from a hot press process.

[0022] Since heat and pressure can be applied in other manufacturingvessels aside from a hot press, the same principles would apply toprevent liquid phase from escaping other such vessels even though aconventional hot press device is not used. Pressure also plays a role inpreventing first material liquid phase from escaping a vessel sincehigher applied pressures may produce a desire for higher viscosity.Temperature and pressure are thus interrelated in preventing liquidphase expulsion and can be optimized according to the principlesdescribed herein to obtain the goals of the various aspects of theinvention.

[0023] Producing a first material liquid phase from at least a portionof the first material can be performed in a variety of manners. Themelting at least a portion of the first material can include meltingsubstantially all of the first material and substantially none of thesecond material. Notably, Se exhibits a melting point of about 220° C.while Ge exhibits a melting point of about 938° C. Such a largedifference in melting point indicates that substantially all of Se as afirst material can be melted while melting substantially none of Ge as asecond material. Other materials can also be selected having a suitabletemperature difference. For example, the first material can exhibit amelting point at least about 100° C. less than a melting point exhibitedby the second material. Accordingly, a first material liquid phase cancomprise substantially all of the first material. Also, the liquid phasecan be formed such that it does not substantially comprise the secondmaterial.

[0024] The phase change characteristics of the first and second materialcan vary depending on the composition of such materials, as well asother factors. Impurities in a single component material, such as Se,can cause the melting point to increase or decrease relative to themelting point of a pure component. Accordingly, depending on theimpurity levels, portions of a material might not change phase fromsolid to liquid at an expected temperature. All that can be expected isfor substantially all of the material to melt when temperature iscontrolled at near the melting point of the primary component. Highertemperatures might be suitable for melting all of the first material. Inthe context of deposition targets, highly pure materials are typicallyused so the amount of material not melted at the melting point is oftencorrespondingly small.

[0025] In the case of a multiple component material such as the firstmaterial or second material, a variety of solid phases can exist in thematerial. Often, a eutectic phase present in the multiple componentmaterial can melt at a significantly lower temperature compared to otherphases of the material. A material may thus begin to melt at onetemperature but not reach substantially complete melting until asignificantly higher temperature. Again, the presence of impurities canresult in small amounts of material not changing phase to a liquid whenseemingly all of the material has melted. In a related sense, a secondmaterial may comprise a small amount of a eutectic phase that meltsduring the melting of the first materiel even though the second materialmelting is largely unnoticed due to the small amount. As an example,such eutectic phase can even be formed due to the presence of impuritiesin an otherwise highly pure material. Accordingly, all that can beexpected is that the first material liquid phase can be formed such thatit does not substantially comprise the second material.

[0026] Of course, an interface can exist between the first materialliquid phase and the solid second material. At the interface, atomicinteractions may occur to form eutectic compositions or othercompositions including elements from both the liquid and solid. Forexample, GeSe, GeSe₂, etc. can form at the interface. However, the firstmaterial liquid phase does not substantially comprise the secondmaterial as a result of small amounts of such compositions forming atinterfaces. The two phases remain largely separate.

[0027] Another advantage of the viscous nature of liquid Se, and perhapsother materials, is that particles remaining solid during the melting ofat least a portion of the first material will not tend to settle out ofthe distribution in the original combination of solid first and secondmaterials. If solid first and second materials are approximatelyhomogenously distributed, then a sufficiently high viscosity can preventa substantial number of particles from settling out of the approximatelyhomogenous distribution. A method according to an aspect of theinvention can include forming an approximately homogenous distributionof the second material throughout the first material liquid phase simplyby providing a homogenous distribution of solid first and secondmaterials when originally combined. The particle sizes discussed aboveand reduction of agglomeration assist in producing a homogenousdistribution in the combined materials. The first and second materialcan be blended in any suitable device known to those skilled in the artto produce an approximately homogenous distribution. Additionally,additives may be included in the combination of first and secondmaterials that are known to those skilled in the art to assist inefficient and/or effective mixing.

[0028] Turning to FIG. 1, a bottom die 2 of a hot press apparatus isshown with first material particles 6 and second material particles 4placed in a cavity 2 a of bottom die 2. FIG. 2 shows punch 8 positionedinside cavity 2 a and applying pressure to first material particles 6and second material particles 4 while such particles are heated. Theheating of the materials is sufficient to form a liquid phase 10 from aportion of first material particles 6. Notably, particles 4,6 are showngenerically without any regard to particle size or shape and are forexplanation purposes only. In FIG. 1, approximately twice the number offirst material particles 6 are shown in comparison to second materialparticles 4. In FIG. 2, approximately 50 volume % (vol %) of firstmaterial particles 6 are melted to form liquid phase 10. Particles 4,6of FIG. 1 form a first volume while particles 4,6 and liquid phase 10 ofFIG. 2 form a second volume smaller than the first volume. FIG. 3 showstarget blank 14 after solidification of liquid phase 10 into matrix 12.FIG. 3 also shows target blank 14 having a third volume less than thefirst volume of FIG. 1, but may be the same or different than the secondvolume.

[0029] As can be seen in the Figures, about 33 vol % of the first volumewas melted to coat second material particles 4 and remaining firstmaterial particles 6. Although about 33 vol % are shown melted in FIG.2, the amount melted is by way of example only and not as a limitationthat 33 vol % is sufficient or necessary to coat second materialparticles 4 and remaining first material particles 6. Surface propertiesof liquid phase 10 and particles 4, 6 constitute a major factor indetermining the volume of liquid phase 10 sufficient to coat particles4, 6.

[0030] Preferably, the second volume of FIG. 2 comprises at least about50 vol % liquid phase of at least one of first material particles 6 andsecond material particles 4. That is, although shown that only firstmaterial particles 6 are melted, it is conceivable that some amount of asecond material could also be comprised by the liquid phase. Morepreferably, the second volume comprises at least about 50 vol % liquidphase of the first material. In the case of GeSe₂ or Ge₃Se₇, the amountof Se present is sufficient to form at least about 50 vol % liquid phasewithout melting any Ge. Ge exhibits a density of about 5.3grams/centimeter³ (g/cm³) and Se exhibits a density of about 4.8 g/cm³at standard state conditions. Ge and Se also have similar atomicweights. Such data is available for other component systems that couldbe included in deposition targets. The data can be used to determinewhether a nominal composition of a target is adequate to produce enoughliquid phase upon melting a first material. It may be desirable to meltat least some of the second material if the liquid phase is otherwisenot sufficient to coat the second material.

[0031] The density of GeSe₂ at standard state conditions is 4.56 g/cm³and it is desirable for the bulk density of a deposition target toexhibit a density near the theoretical pure component density.Approximating theoretical density can also be desirable in depositiontargets formed of other materials. The method according to the presentaspect of the invention can obtain a deposition target bulk density ofat least about 95% of theoretical density. Preferably, the methodproduces at least about 97% of theoretical density, or more preferably,at least about 98% of theoretical density. The high percent oftheoretical density possible with the present method is difficult toobtain simply by conventional hot pressing of a solid first materialcombined with a solid second material. It is even difficult to obtain byhot pressing ground-up single phase GeSe₂. The specific mechanism bywhich the present invention achieves a high percent of theoreticaldensity is not well understood. It is believed that densification ofcombined first and second materials involves a combination of mechanismsthat may include particle rearrangement, solid state diffusion, and theformation of the liquid phase, as such mechanisms are known to thoseskilled in the art. Inadequate heating at too low a temperature and/orfor too short a time and/or inadequate compression can produceinadequate densification.

[0032] In the present aspect of the invention, applying heat andpressure can include heating to a temperature of less than about themelting point of the second material under compression of from about6.9×10⁶ to about 28×10⁶ Pascals (about 1,000 to about 4,000 pounds/inch²(psi)). Preferably, the heating can be conducted at a rate of from about200 to about 400° C. per hour. As an example, the heating can attain atemperature of about 225° C. Such temperature has proven sufficient tomelt substantially all of the Se in a combination of Ge and Se powdersunder compression.

[0033] After forming a suitable liquid phase, the present method caninclude solidifying the first material liquid phase to define acomposite target blank that includes an approximately homogenousdistribution of the solid second material in a matrix of the solidifiedfirst material. Alternatively, the liquid phase can comprise at leastone of the first material and the second material and cooling the heatedmaterial can form a solid matrix from the liquid phase. The cooledmaterial thus defines a composite target blank comprising some of thesolid particles in the solid matrix. Cooling can include removing heatto attain about an intermediate temperature, maintaining about theintermediate temperature for from about 45 to about 90 minutes, andcooling further to a room temperature of from about 20 to about 25° C.

[0034] Most preferably, the hot pressing attains a temperature ofgreater than about 200° C. and the cooling includes maintaining apressure applied during the hot pressing while removing the heat toattain about 200° C. Temperature can be maintained at about 200° C. forfrom about 15 to about 60 minutes followed by further cooling to roomtemperature and removing the pressure when room temperature is attained.In the method described above, a highly densified composite depositiontarget can be produced having a composition determined largely by theprecision and accuracy with which solid materials are quantitativelyblended. Further processing of blended components can produce ahomogenous distribution of selected solid materials in a matrix ofsolidified other selected materials. The homogeneity and densitycontribute to the high quality of the deposition target.

[0035] In a further aspect of the invention, a PVD target can include amatrix of a first material and an approximately homogenous distributionof particles of a second material throughout the first material matrix.The first material matrix can comprise a first metal, and the particlesof the second material can comprise a powder of a second metal. Thetarget can include at least about 50 vol % matrix. The matrix cancomprise at least about 99.99 wt % Se on a metals basis and the secondmaterial can comprise at least about 99.99 wt % Ag or Ge on a metalsbasis. For example, Se and Ge (and/or Ag) can be provided at a puritylevel of about 99.999 wt %.

[0036] The matrix can comprise substantially all of the first materialand may be a continuous matrix encapsulating the second material.Preferably, the matrix does not substantially comprise the secondmaterial. The particles of the second material can exhibit particlesizes no greater than about 100 mesh, or preferably no greater thanabout 325 mesh. Further, any second material particle agglomerations canexhibit a size no greater than about 100 mesh. A target comprising fromabout 25 to about 50 wt % of at least one of Ag or Ge in an Se matrixmay be particularly useful and valuable. For example, the target mayexhibit a stoichiometric atomic ratio of Ge to Se of about 1:2 or about3:7. Even so, the ratio of Ge to Se can correspond to another knowngermanium selenide or to a non-stoichiometric composition.Advantageously, the films deposited from the above described targets canexhibit substantial homogeneity of the same ratio of componentscontained in the targets.

[0037] An exemplary backing plate/target assembly encompassed by thepresent invention is shown in FIGS. 4 and 5 as assembly 30. Assembly 30comprises a backing plate 32 bonded to a target blank 34. Backing plate32 and target blank 34 join at an interface 56, which can comprise, forexample, a diffusion bond between the backing plate and target or asolder bond. Target blank 34 can comprise, for example, a GeSe₂ orGe₃Se₇ composite target blank. Backing plate 32 and target blank 34 cancomprise any of numerous configurations, with the shown configurationbeing exemplary. Backing plate 32 and target 34 can comprise, forexample, an ENDURA™ configuration, and accordingly can comprise a roundouter periphery. FIG. 5 shows assembly 30 in a top-view, and illustratesthe exemplary round outer periphery configuration.

EXAMPLE NO. 1

[0038] A powder blend having the nominal composition GeSe₂ was preparedand loaded into a hot press die. The die was loaded into a hot presschamber and 2,500 psi was applied to the die assembly. The hot presschamber was evacuated, backfilled with argon gas, and maintained at apressure of approximately 500 Torr. The temperature was increased fromambient temperature to 225° C. at a rate of approximately 300° C. perhour. 225° C. was maintained for 60 minutes. The temperature was reducedto 200° C. and maintained for 45 minutes. The temperature was reduced toroom temperature and then pressure was released. The resulting materialexhibited a 97% theoretical density.

EXAMPLE NO. 2

[0039] The same procedure as described in Example 1 was carried outexcept that the temperature of 225° C. was maintained for 68 minutesinstead of 60 minutes. A material with a greater than 98% theoreticaldensity was produced.

EXAMPLE NO. 3

[0040] The same procedure as described for Example 1 was carried outexcept for the powder blend had a nominal composition of Ge₃Se₇ and thetemperature of 225° C. was maintained for 70 minutes instead of 60minutes and material exceeding 99% theoretical density was produced.

[0041] The invention has been described in language more or lessspecific as to structural and methodical features. It is to beunderstood, however, that the invention is not limited to the specificfeatures shown and described, since the means herein disclosed comprisepreferred forms of putting the invention into effect. The invention is,therefore, claimed in any of its forms or modifications within theproper scope of the appended claims.

I (We) claim:
 1. A method comprising: combining solid Se and at leastone of solid Ag or solid Ge; melting at least a portion of the Sesufficient to coat the Ag or Ge and any remaining Se, the melted portiondefining an Se liquid phase; forming an approximately homogenousdistribution of the Ag or Ge throughout the Se liquid phase; solidifyingthe Se liquid phase to define a composite material comprising anapproximately homogenous distribution of the solid Ag or Ge in a matrixof the solidified Se.
 2. The method of claim 1 wherein the solid Se andthe at least one of solid Ag or solid Ge are metal particles and exhibitparticle sizes no greater than about 325 mesh.
 3. The method of claim 1wherein the Se comprises at least about 99.99 weight percent (wt %) Se,the Ag or Ge respectively comprise at least about 99.99 wt % Ag or Ge,and the composite material comprises from about 25 to about 50 wt % ofthe at least one of Ag or Ge in the Se matrix.
 4. The method of claim 1wherein the composite material comprises at least about 50 volumepercent (vol %) matrix.
 5. The method of claim 1 wherein the compositematerial is formed as a physical vapor deposition target blank.
 6. Themethod of claim 1 wherein the at least one of solid Ag or solid Geconsists of solid Ge.
 7. A physical vapor deposition target formingmethod comprising: combining a solid first material and a solid secondmaterial; melting at least a portion of the first material sufficient tocoat the second material and any remaining first material, the meltedportion defining a first material liquid phase; forming an approximatelyhomogenous distribution of the second material throughout the firstmaterial liquid phase; solidifying the first material liquid phase todefine a composite target blank comprising an approximately homogenousdistribution of the solid second material in a matrix of the solidifiedfirst material.
 8. The method of claim 7 wherein the first and secondmaterials comprise metals.
 9. The method of claim 7 wherein the solidfirst and second materials comprise particles and exhibit particle sizesno greater than about 100 mesh.
 10. The method of claim 7 wherein thefirst material comprises Se and the second material comprises Ge. 11.The method of claim 7 wherein the first material comprises Se and thesecond material comprises Ag.
 12. The method of claim 7 furthercomprising combining at least one additional solid material with thesolid first and second materials.
 13. The method of claim 7 wherein themelting a least a portion of the first material and the forming anapproximately homogenous distribution occur together and comprise hotpressing.
 14. The method of claim 7 wherein the melting a least aportion of the first material comprises melting substantially all of thefirst material and substantially none of the second material.
 15. Themethod of claim 7 wherein the composite target blank comprises at leastabout 50 vol % matrix.
 16. The method of claim 7 wherein the meltingoccurs at a temperature of less than about a melting point of the secondmaterial.
 17. The method of claim 7 wherein the melting the firstmaterial occurs in a vessel while heating the first material to atemperature and compressing the first material at a pressure, the firstmaterial liquid phase exhibiting a sufficiently high viscosity at thetemperature to prevent a substantial amount of the first material liquidphase from escaping the vessel at the pressure.
 18. The method of claim7 wherein the melting the first material occurs at a temperature, thefirst material liquid phase exhibiting a viscosity at the temperaturesufficiently high to prevent a substantial amount of second materialfrom settling out of the approximately homogenous distribution in thefirst material liquid phase.
 19. The method of claim 7 wherein thecomposite target blank exhibits a bulk density of at least about 95% oftheoretical density.
 20. A physical vapor deposition target formingmethod comprising: combining solid particles of a first metal with solidparticles of a second metal; applying heat and pressure to the combinedsolid particles and forming a heated material comprising at least about50 vol % liquid phase of at least one of the first metal and the secondmetal; and cooling the heated material to form a solid matrix from theliquid phase, the cooled material defining a composite target blankcomprising some of the solid particles in the solid matrix.
 21. Themethod of claim 20 wherein the first metal comprises Se and the secondmetal comprises Ge.
 22. The method of claim 20 wherein the first metalcomprises Se and the second metal comprises Ag.
 23. The method of claim20 wherein at least one of the first metal and second metal comprise aplurality of metallic elements.
 24. The method of claim 20 furthercomprising separating agglomerations of the solid particles prior toapplying heat and pressure.
 25. The method of claim 20 wherein the solidparticles of the first and second metals exhibit particle sizes nogreater than about 325 mesh.
 26. The method of claim 20 wherein theliquid phase does not substantially comprise the second metal and theheated material comprises an approximately homogenous distribution ofsolid particles of the second metal throughout the liquid phase.
 27. Themethod of claim 20 wherein the liquid phase comprises substantially allof the first metal.
 28. The method of claim 20 wherein the applying heatand pressure comprises heating to a temperature of less than about amelting point of the second metal under compression of from about6.9×10⁶ to about 28×10⁶ Pascals (about 1000 to about 4000 pounds/inch²).29. The method of claim 20 wherein the applying heat and pressure occurtogether in a vessel, the liquid phase exhibiting a sufficiently highviscosity during the applying to prevent a substantial amount of theliquid phase from escaping the vessel.
 30. The method of claim 20wherein the particles remaining solid during the applying heat andpressure form an approximately homogenous distribution throughout theliquid phase, the liquid phase exhibiting a viscosity sufficiently highto prevent a substantial number of particles from settling out of theapproximately homogenous distribution.
 31. A physical vapor depositiontarget forming method comprising: combining a first powder comprising afirst metal with a second powder comprising a second metal, the combinedfirst and second powders having a first volume and the first metalexhibiting a melting point at least about 100° C. less than a meltingpoint exhibited by the second metal; applying heat and pressure to thefirst volume and changing the first volume to a second volume, thesecond volume comprising at least about 50 vol % liquid phase of thefirst metal; and cooling the second volume into a composite target blankcomprising an approximately homogenous distribution of at least thesecond powder throughout a solid matrix comprising the first metal. 32.The method of claim 31 wherein the first metal comprises Se and thesecond metal comprises Ge.
 33. The method of claim 31 wherein the firstmetal comprises Se and the second metal comprises Ag.
 34. The method ofclaim 31 wherein the first and second powders exhibit particle sizes nogreater than about 325 mesh, the method further comprising screening atleast one of the first and second powders with a 100 mesh screen toseparate agglomerations.
 35. The method of claim 31 wherein the applyingheat and pressure comprises heating to a temperature of less than aboutthe melting point of the second metal at a rate of from about 200 toabout 400° C. per hour while under compression of from about 6.9×10⁶ toabout 28×10⁶ Pascals (about 1000 to about 4000 pounds/inch²).
 36. Themethod of claim 31 wherein the cooling the second volume comprisesremoving heat to attain about an intermediate temperature, maintainingabout the intermediate temperature for from about 45 to about 90minutes, and cooling further to a room temperature of from about 20 toabout 25° C.
 37. The method of claim 31 wherein the composite targetblank exhibits a bulk density of at least about 97% of theoreticaldensity.
 38. A physical vapor deposition target produced by the methodof claim
 7. 39. A physical vapor deposition target produced by themethod of claim
 20. 40. A film produced by the physical vapor depositiontarget of claim
 38. 41. A film produced by the physical vapor depositiontarget of claim
 39. 42. A composite material comprising a Se matrix as asolid phase separate from an approximately homogenous distribution of atleast one of solid Ag or solid Ge throughout the Se matrix.
 43. Thematerial of claim 42 wherein the at least one of solid Ag or solid Gecomprises metal particles and exhibits particle sizes no greater thanabout 325 mesh.
 44. The material of claim 42 wherein the Se comprises atleast about 99.99 wt % Se, the Ag or Ge respectively comprise at leastabout 99.99 wt % Ag or Ge, and the composite material comprises fromabout 25 to about 50 wt % of the at least one of Ag or Ge in the Sematrix.
 45. The material of claim 42 wherein the composite materialcomprises at least about 50 vol % matrix.
 46. The material of claim 42wherein the composite material is a physical vapor deposition targetblank.
 47. A physical vapor deposition target comprising a matrix of afirst material and an approximately homogenous distribution of particlesof a second material throughout the first material matrix.
 48. Thetarget of claim 47 wherein the first and second materials comprisemetals.
 49. The target of claim 47 wherein the second material particlesexhibit particle sizes no greater than about 100 mesh.
 50. The target ofclaim 47 wherein any second material particle agglomerations are nogreater than about 100 mesh.
 51. The target of claim 47 wherein thefirst material comprises Se and the second material comprises Ge. 52.The target of claim 47 wherein the first material comprises Se and thesecond material comprises Ag.
 53. The target of claim 47 furthercomprising a third material.
 54. The target of claim 47 wherein thetarget comprises at least about 50 vol % matrix.
 55. The target of claim47 wherein the matrix is continuous.
 56. The target of claim 47 whereinthe first material exhibits a melting point at least about 100° C. lessthan a melting point exhibited by the second material.
 57. The target ofclaim 47 wherein the target exhibits a bulk density of at least about95% of theoretical density.
 58. The target of claim 47 wherein thematrix does not substantially comprise the second material.
 59. Aphysical vapor deposition target comprising at least about 50 vol %matrix and an approximately homogenous distribution of a powderthroughout the matrix, the matrix comprising a first metal and thepowder comprising a second metal.
 60. The target of claim 59 wherein thepowder exhibits particle sizes no greater than about 325 mesh.
 61. Thetarget of claim 59 wherein the first metal comprises Se and the secondmetal comprises Ge.
 62. The target of claim 59 wherein the first metalcomprises Se and the second metal comprises Ag.
 63. The target of claim59 wherein at least one of the first metal and second metal comprise aplurality of metallic elements.
 64. The target of claim 59 wherein thematrix comprises substantially all of the first metal and does notsubstantially comprise the second metal.
 65. The target of claim 59wherein the target exhibits a bulk density of at least about 97% oftheoretical density.
 66. A physical vapor deposition target comprising acontinuous matrix of Se encapsulating an approximately homogenousdistribution of a powder throughout the Se matrix, the powder comprisingat least about 99.99 wt % of at least one of Ag or Ge on a metals basisand the target exhibiting a Se matrix with a combined Ag and Ge contentfrom about 25 to about 50 wt %.
 67. The target of claim 66 wherein thetarget comprises at least about 50 vol % matrix.
 68. The target of claim66 wherein the matrix comprises substantially all of the Se and does notsubstantially comprise the Ag or Ge.
 69. The target of claim 66 whereinthe target exhibits a bulk density of at least about 98% of theoreticaldensity.
 70. The target of claim 66 wherein the powder comprises about99.99 wt % Ge.